It could be a REAL Ford Sierra... as of this writing, the car is 28 years old (if it's indeed a 1984 model). Which would mean that it could have been legally imported from Europe (perhaps Germany, Spain, etc or another country that also had LHD - left hand drive).

In the US, cars older than 25 years old can be imported from other countries, including overseas countries with a lot less red tape hassle. In Canada, the cars need only be 15 years old, though I think there might be a stipulation that they have to LHD.

There's a small but loyal following of these cars, so someone who really wanted one may have gone to the effort of importing this one from overseas. The headlights and center tail light panel look different than the ones sold here as Merkur XR4Ti's (then again, they could have been swapped in). However, it's got a center mounted third brake light, which (AFAIK) did not become installed until 1986 on US and Canadian spec cars. Not sure about Europe. Or maybe it's a spolier from a newer model bolted on?

I learnt to drive on a 1990 Ford Sierra over here in the UK - a lot of fun, and the only rear drive car I've owned. As far as the explanation of XR4Ti, I'm not sure if I'd along with all of the explanation.

Over here in Europe the XR badge was put on the "performance" Ford models, and didn't have anything to do with whether it was front or rear drive. The number also was to do with the model, rather than the number of cylinders. Hence you had the Sierra XR4i, Escort XR3i and Fiesta XR2. All these cars were 4-cylinder. The Sierra was rear drive whilst Escort and Fiesta were front drivers. In the early 90s you did get a four wheel drive Sierra (For homologation for the World Rally Championship) which was called the XR4x4.

Finally, the i on cars over here always stood for fuel injection rather than intercooled.

Obviously everything I just said may be wrong in relation to Merkur, but there you go...